1. Field of Endeavor
The present invention relates to microfluidic particle separators and more particularly to microfluidic ultrasonic particle separators with engineered node locations and geometries.
2. State of Technology
The article, “Chip integrated strategies for acoustic separation and manipulation of cells and particles,” by Thomas Laurell, Filip Petersson, and Andreas Nilsson in Chem. Soc. Rev., 2007, 36, 492-506, states: “Chip integrated strategies for acoustic separation and manipulation of cells and particles,” by Thomas Laurell.” The article includes the state of technology information quoted below and drawing FIGS. 1A, 1B, and 1C are copies of FIGS. 5, 6 and 7 from the article. The article, “Chip integrated strategies for acoustic separation and manipulation of cells and particles,” by Thomas Laurell, Filip Petersson and Andreas Nilsson in Chem. Soc. Rev., 2007, 36, 492-506, is incorporated herein in its entirety for all purposes.
“FIG. 5 Schematic cross-section of separation chip utilizing the Lund method. The silicon separation channel is sealed by a boron silica glass lid and is actuated from below using a piezoelectric ceramic.” [FIG. 1A]
“FIG. 6 Illustrated cross-section (along the dashed line in FIG. 7) of a separation channel showing negative w-factor particles (e.g. lipid particles) collected in the pressure antinodes by the side walls and positive w-factor particles (i.e. red blood cells) in the pressure node.” [FIG. 1B]
“FIG. 7 Illustration of separation of negative w-factor particles (black—centre outlet) and positive w-factor particles (grey—side outlets) in 45 u design chip.” [FIG. 1C]
“The Lund-method for acoustic separation of suspended particles from their medium is based on a laminar flow microchannel that is ultrasonically actuated from below, using a piezoelectric ceramic (FIG. 5). The width of the channel is chosen to correspond to half the ultrasonic wavelength, thereby creating a resonator between the side walls of the flow channel in which a standing wave can be formed. The induced standing wave is thus generated orthogonal to the incident ultrasonic wave front. As suspended particles with a positive w-factor perfuse the channel they are moved, by means of the axial PRF, towards the pressure nodal plane along the channel centre, while those with a negative w-factor are moved towards the anti-nodal planes close to the side walls (FIG. 6).”
“The end of the separation channel is split into three outlet channels, thus allowing the positive w-factor particles to exit through the centre outlet and the negative w-factor particles to exit through the side outlets, provided that all outlet flow rates are alike (FIG. 7). The separation efficiency of positive and negative w-factor particles is defined as the fraction of particles exiting through the centre and side outlets respectively.”